Olfactory responses of lobsters(Homarus Americanus)to solutions from prey species and to seawater extracts and chemical fractions of fish muscle and effects of antennule ablation

Abstract

Tank water from intact prey and extract of Echinoderms are practically non‐stimulatory to lobsters whereas extracts of molluscs crustaceans and fish are highly stimulatory. Extract of cod muscle prepared by freeze‐drying drip from thawing cod chunks is more effective in terms of concentration required to produce 50% response from lobsters than extracts prepared by homogenization or stirring of muscle tissue in sea water. Homogenized cod muscle extract and freeze‐dried material prepared from the latter (yield 8.8 %) elicit similar responses provided equivalent weights are used. Stirred cod, herring and flounder muscle extracts elicit similar responses at equivalent concentrations. The attractive substance in cod muscle is soluble in distilled water and in sea water and withstands boiling. It is dialysable. Preliminary tests with ion exchange resin columns indicate amphoteric and basic compounds are stimulatory, neutral acidic and volatile compounds are non‐stimulatory. The substance is soluble in ethyl alcohol but not in hexane or chloroform indicating it is non‐lipid and is a highly polar material. Observations of the olfactory response of lobsters with the medial, lateral and medial and lateral branches of the antennule bilaterally ablated, indicate that the lateral branch performs a chemoreceptive function and that the medial branch assists in chemoreception perhaps through orientation to water current.